Compressor



March 2, 1937. M. w. KENNEY- COMPRESSOR Filed May 14, 1934 3 Sheets-Sheet 1 fiuerzi'ar: m/ya/zlon/lllkrzzgg @5 @611 l mafia/ March 2, 1937. M. w. KENNEY 2,072,307

. COMPRESSOR Filed May 14, 1954 5 Sheets-Sheet 2 QM 077W @6 March 2, 1937. M, w, KENNEY 2,072,307

COMPRESSOR Filed May 14, 1934 3 Sheets-Sheet 3 Patented Mar. 2, 1937 PATENT oFFicE 2,072,307 co rnEssoa Mahlon W. Kenney, Chicago, 111., assignor, by mcsne assignments. to Reconstruction Finance Corporation, Chicago, 111., a corporation Application May 14, 1334, Serial No. 725,473

12 Claims.

This invention relates,in general, to motorgenerator units, and has more particular refer-v ence to a unit comprising fluid pressure generator powered by. an electrically'operated motor, the

unit being adapted, more especially, for use as a refrigerant compressor in a refrigerating system of the so-called compression-evaporation type wherein a suitable refrigerating medium, in gaseous form, is cyclically compressed, condensed to '10 liquid form by cooling and evaporated for the purpose of absorbing heat.

The inventionhas for an important object the provision of an improved device particularly well adapted foruse in refrigerating systems as ap- 15 plied in domestic refrigeration and, to thisend, characterized by simplicity of construction, whereby assembly of the unit is facilitated and manufacturing costs consequently reduced, the device being compact, efficient in operation, providing for substantially noiseless operation and including simple, self-contained means for adequately lubricating its operating parts whereby the same is adapted for continuous operation over long periods of time without attention, and consequently may be used to advantage in domestic refrigerators.

Another important object is to provide a motor.

compressor unit of the character mentioned wherein the compressor and its driving means,

comprise a sealed unit whereby the necessity of sealing the compressor shaft against the escape of fluid under pressure, is eliminated, the invention including the provision of means for adequately lubricating the moving parts of the sealed unit so that the same may operate continuously,

without attention as to lubrication, during extended periods.

Among the other important objects of the invention is to utilize the working medium as a 40 heat transfer agency within the sealed unit for cooling the operating parts thereof, and to this and eccentric with respect thereto, the sleeve being journalled on outer cylindrical surfaces of a support pedestal and the impeller having a shaft journallcd in the pedestal eccentric with respect to the sleeve whereby to facilitate assembly of the parts on the pedestal by merely dropping them mm position; to facilitate the assembly of the sleevelike cylinder by arranging the same for --endwise supporton the impeller'in substantially ment of the cylinder; to provide-a common guid- 15 ingandsupport element for-both cylinder and impeller; toform the cylinder element and the support pedestal-with co-operating surfaces providing a muilier chamber; and in general to simplify and reduce the cost of devices of the 20 character mentioned through the several unique features hereinafter disclosed.

Numerous other objects, inherent advantages, and functions of the invention will be apparent as the same is more fully understood from the 25 following description, which, taken in connection with the accompanying drawings, discloses a pre-' ferred embodiment of the invention.

Referring to the drawings:

' Figure 1 is a diagrammatic view of a compres- 30 sion-evaporation refrigerating system having a sealed motor-compressor unit embodying the present invention;

, Figure 2 is a diagrammatic view of an electrical system, which may be used to supply power for 35 operating the refrigerating system illustrated in Figure 1;

Figure 3 is a view. in vertical section taken through the motor-compressor unit of the system shown in Figure 1; 40

Figure 4 is a view in horizontal section taken substantially alongthe line 4-4 in Figure. 3;

Figure 5 is a view in vertical secticntaken substantially along-the line, 5-5 in Figure 4; and

Figures 6, 7, andB are horizontal views taken substantially along the lines 6-6, 1-1, and 8-4 in Figure 3.

To illustrate the invention, I have shown on the drawings a fluid-forcing device particularly adapted for use as a compressor in a refrigerating system of the compression-evaporation type, and while I contemplate the use of devices embodying the invention particularly in combination forming a refrigerating system, it will be obvious that the invention is not necessarily restricted in every feature to compressors or to devices used for refrigerating purposes. In fact, the invention includes features adapted to hydraulic devices generally, and embodies features of advantage not necessarily restricted to devices incorporated in a compression-evaporator system. The invention, however, is particularly well adapted for embodimerit in fluid-forcing means, .namely a compressor, to provide a substantially leak-proof device, noiseless and efllcient in operation over long periods of time without attention, whereby the same is especially well suited forum in refrigerating systems applied to domestic service.

To provide the foregoing characteristics, the compressor is formed as a sealed unit including fluid-forcing means II and driving means I3, preferably comprising an electric motor, the fluid-forcing and driving means being housed in a substantially hermetic casing Il, formed in any suitable fashion, and preferably comprising a base IS on which the fluid-forcing and driving means are supported in position extending upwardly of the base, and a cover section 2! secured on and to the base in position to enclose the fluid-forcing and driving means. The cover section 2| cooperates to form hermetically sealed housing for the mechanism of the unit.

The base I 9 is preferably formed, as a substantially cup-shaped casting of material sufflciently strong to form a rigid support for the operating elements of the motor compressor unit.

The casting preferably includes an outstanding peripheral flange 13 at its upper edge, the flange being thickened in its outer portion to form an annular rim 15 provided at spaced apart points therein with threaded sockets TI. The cover section 2| is also preferably of cup-shaped form, and is preferably made of heat-conducting material in sheet form, thereby serving to dissipate the heat generated by the operation of the mechanism within the casing. The cover section may be conveniently fabricated by spinning or otherwise forming sheet metal stock and, as formed, is preferably provided with an outstanding peripheral flange I9 so that when the cover section is inverted on the base, the flange I9 will register with'the rim II, and the casing portions may be sealingly secured together in position to enclose the fluid-forcing and driving elements II and I3 by interposing an annular gasket II between the rim 15 and flange 19, and

by securing the rim I5 and flange I9 together in any suitable manner as by means of the annular clamping ring 83, which is applied behind the flange I9 and the bolts 85, which penetrate perforations in the ring 83 and flange 19 and thread into the socket TI of the rim I5.

The bottom of the cup-shaped casting is formed with an upwardly facing seat 23 on which is mounted a pedestal 25 having an upstanding portion 21 and a flanged end 29 which rests upon the seat 23 being secured thereto in any suitable or preferred fashion as by means of bolts or studs 3|. The compressor and movable portion of its driving motor are supported on the pedestal 25.

The fluid-forcing mechanism I I preferably comprises a cylindrical sleeve 33 having a lower portion 35 embracing and rotatingly seated upon the upstanding portion 21 of the pedestal and a portion 31 extending upwardly of the pedestal to provide a working chamber within the sleeve above the pedestal. The compressor II also comprises an impeller member 3! of substantially cylindrical shape and rotatably mounted on the pedestal, and supported in the working chamber within the sleeve above the pedestal, said impeller-member 39 being of lesser diameter than the internal diameter-of the working chamber, and being mounted with its rotating axis eccentric with respect to that of the sleeve to a degree such that the impeller, on one side of the compressor, isin contact with the inner surface of the sleeve leaving a crescent-shaped working space H between the outer surface of the impeller and the inner surface of the sleeve.

Inlet means, comprising a manifold H1, in communication with one end of the crescentshaped working space, and outlet means, comprising a duct III, in communication with the other end of the crescent-shaped working space, are provided to deliver the work material to and from the work space.

The impeller 38 also is formed with one or more channels I21 extending parailel to and spaced from its axis and a radial slot I25 is formed between each channel and the cylindrical surface of the impeller. The channels I21 and slots I29 extend from end to end of the cylindrical portion of the impeller and a fluidforcing vane or blade I3I is carried in each slot, said blades being long enough to extend from end to end of the impeller. The outer edges of the blades are slightly rounded so that the same' may engage and press upon the inner surface of the sleeve at all times during the rotation of the sleeve and impeller, and define, in the working space, one or more compression chambers adapted cyclically to increase and decrease in volume during the rotation of the parts.

In order to support the sleeve and impeller in the proper eccentric relationship, the upstanding portion 21 of the pedestal is formed with outer cylindrical walls 43 upon which the lower end 35 of the sleeve forms a running flt. The inner surfaces of the sleeve are cut away to form an annular space 45 between the sleeve and the cylindrical sleeve-bearing portion of the pedestal so that the sleeve bears upon the pedestal at spaced annular portions 41 at the opposite ends of the space 45. The upstanding portion 21 of the pedestal 25 is also-provided with an axial bore 49 forming a Journal eccentric with respect to the outer cylindrical pedestal surface 43 and the impeller member 39 is formed with an axial shaft 5i which extends into the journal 49, the shaft 5| being preferably formed with spaced bearings 53 which slidingly flt into the journal 49 whereby to rotatably support the impeller on the pedestal in eccentric position with respect to the sleeve. The upper end of the pedestal providesa step-bearing on which the impeller 33 is rotatably supported at its lower end so that to assemble the impeller on the pedestal, it is merely necessary to insert the shaft 5| in the journal 48 and permit'the weight of the impeller to retain it in position upon the step-bearing at the upper end of the pedestal. The upper end of the sleeve 33 is or may be provided with a bearing plate 55, which may, of course, be formed integral with the sleeve, but which is preferably formed as a separate plate, and secured in position by means of the bolts or studs 51. This plate is of annular shape having a substantial opening 59 and is adapted to rest upon the upper end of the impeller member and support the sleeve in position, so that after the impeller is assembled on the pedestal, the sleeve may be assembled in operating position by merely dropp it over the impeller and the pedestal.

Means is provided to cause the impeller and sleeve to rotate in unison in order to cause the crescentshaped space 4| to move relatively around the -axis of the sleeve in order to perform the fluid 10 trated by the arrow in Figure 8 of the drawings.

each compression space, defined between the sleeve and impeller between the blades I3I, will expand while'said compression space is, in communication with the inlet manifold 1. "Each i8 compression space will havemaximum volumeat the instant that the trailing blade, defining said space, registers, with the trailing wider end of the intake manifold and cuts off the compression space from further communication therewith. As

20 the parts continue to rotate, the compression cross-sectional configuration.

space, with work material entrapped therein, will decrease in diametric volume capacity'as the surfaces of the sleeve and impeller come together as a result of the rotation of the parts so that the III as soon as the leading blade of the compression space has uncoveredsaid duct. Any suitable means may, of cours, be utilized to cause the sleeve and impeller to rotate on the pedestal in unison, but I prefer to form the impeller with an upwardly extending stub-shaft BI of nonecircular This stub-shaft extends through the opening 59 and is fitted with a radially extending arm 33. The sleeve also 'is formed with a projection comprising a stud 65 adapted to engage the arm 63 so that when the sleeve is rotated, as by means of the motor I3, the stud 65 will bear against one side of-the arm 63 and cause the impeller to rotate on its axis The stud 65 is preferably carried on the end of an arm 61, which in turn, is secured to the end of the sleeve by means of the bolts B'I, although the stud may, of'course, be formed and mounted on the sleeve in any suitable or preferred fashion. In addition, the pper end of the sleeve may carry a fan ,element 69 for the purpose of within the housing I'I.

Any suitable means I8 may, of course, be used to drive the compressonbut I prefer to utilize an electric motor having an annular stator 81 secured in substantially horizontal position to the base I9, the stator resting in a seat 89 formed in theopen end of the cup-shaped casting forming the base I9 and being held in position in any suitable fashion as by the studs 9 I, which thread into threaded sockets 93 formed in the base,

In the illustrated embodiment, the stator 81 is provided with electrical windings 95, which may be energized from an electrical power source external to the casing of the unit by means of conductors 91, which are electrically connected with the windings and which extend from the casing through sealed plugs 99 mounted in a wall of the casing I9. The plugs 39 may comprise substantially cylindrical sleeves IIII having externally threaded ends I03 fitting into threaded perforat a sleeve 33 in position within the annular stator 81 so that when the sleeve isassembled on the pedwork material-will become compressed, and may, be expelled under pressure through the outlet duct circulating air mechanically integral part of the sleeve, I am not only able to reduce the overall size and weight of the unit, but also am able to'eiiminate the provisions of additional bearings for the rotating motor element. Furthermore, I am able to facilitate the assembly of the unit, since the rotating part of the motor is fitted on andassembled in the structure simultaneously with the compressor s eeve.

The bottom'of the base I3 is formed with an inlet duct I09, one end of which opens in the seating surface 23 in position to' communicate with thelower end 'of a duct III formed axially in' the pedestal. The 'duct III! has another end opening on a side wall of the casing I9, and the casing carries a fitting 3, whereby said end of the duct I09 may be connected to refrigerant conduit H5, throughwhich-thework material to be compressed may bedell'v'ere'dto the unit. The pedestal duct III opens intothe intake manifold,

1 which is rormes s a cutaway portion in at the upper end 'ofthe pedestal; Thec'utaway portion II! has an vinner edge extending substantially opposite the edge of the-impeiier fl and an outer edge coincidingfwith theinm-ir wall of the sleeve. The cutaway'portion lies opposite one arm of the crescent-shaped work space-GI and extends, in the illustrated embodiment, from a point near the point of contact between the impeller and the s1eeve,-a distance substantially one-third of the circumference of the pedestal. The discharge duct means-leading from the work space H into the casing I1. is or may be provided in the sleeve 33 or the pedestal 35, or both, whereby working material, compressed in the working space by the rotation of the'sleeve and impeller, may be expelled therefrom into the interior of the casing II, from whence the compressed work material may escape through'a discharge fitting I I9, which is preferably formed'in the cover section 2| of the casing. Asshownin Figure 3 of the drawings,

the discharge duct means,- permitting the escape of the work material from the compression space, comprises the duct I2I located at the upper end of the pedestal in position communicating with the arm of the crescent-shaped work space remote from the intake manifold H1.

The duct I2I also communicates with the space 45 between the pedestal and the lower portions of the sleeve so that the compressed work medium may be delivered from the work chamber into this space, which functions to a certain extent as a mufller for ironing out the pulsating effect imparted to the work material in being compressed and discharged. The'lower' portions of the sleeve also are provided with perforations I25 communicating with the annular'chamber and the interior of the casing I'I outside of the sleeve 33, and through which perforations, the compressed medium may escape into the casing'and thence through the outlet I I9. It is also possible to provide a valve discharge eifect'by shortening the duct I2I so that it does not communicate with the chamber 45 and-by arranging the perforation I25 in the sleeve portion I23, there being at least one perforation I25 for each compression space defined by the vanes I3I of the impeller and properly spaced circularly in the sleeve, care being taken' to arrange the perforations I25 in such a way that they do not communicate with the inlet manifold H1 at any time during the rotation of the sleeve. With such an arrangement, the discharge is normally closed except when the perforations I25 register with the duct I2I, the perforations I25 being so disposed in the sleeve that they register with the duct I2I atthe 1nstant when it is desired to discharge the compressed material. For instance, the perforations I25 may be arranged to discharge the compressed medium only after the pressure within the compression space has attained a predetermined value so as to prevent material under pressure within the casing I1 from flowing back into the compression space through the outlet port. Alternately, the perforations I25 may be arranged as shown and the upper end of the chamber 45 provided with extensions at proper intervals to register with the shortened duct I2I, thus providing a 25 valved discharge into the chamber 45 from whence the compressed medium may escape through the perforations I25.

In order to provide adequate lubrication for the working parts of the unit, the base I9 provides a. reservoir for a lubricating medium I33, and the base is formed with a conduit I35 communicating the lowermost portion of this lubricant reservoir with a chamber I31, which opens on the seat 23in position communicating with the lower end of the pedestal channel 49 in which the impeller shaft 5| is journaled. The bearing means 53 and the journal, in which the same is mounted, are formed with co-operating means the opening 59 and be thrown outwardly onto the walls of the cover section 2I, and will thence drain back into the reservoir contained in the base I9. During its passage through the channels I21, part of the lubricant will escape radially outwardly through the slots I29 in which the blades I3I are mounted, and will serve to lubricate the blades during the radially reciprocating movement of the same in the slots as well as to lubricate the edges of the blades which slide in contact with the inner surface of the sleeve. Lubricant, so delivered, in excess of that required for adequate lubrication of the blades, will be delivered out of the working space with the compressed work medium through the outlet duct I2I. and will accumulate in the space 45 and serve to lubricate the cooperating. bearing surfaces of the pedestal and sleeve. Eventually, this oil also will flow back into the reservoir in the base I9, and to facilitate such flow,'I may form ducts I in the lower portions of the sleeve.

As a lubricating medium, I prefer to employ a suitable mineral oil and contemplate the compressor more especially for use in the compression of a refrigerating medium comprising dichloromethane with which mineral oils do not form solution to any great extent, so that even though the lubricant and work medium are mingled together in the compression space, the compressed material, in gaseous form, expelled from the work space into the housing I1, does not require treatment to separate it from the lubricant, but the lubricant drains to the reservoir in the'base II while the compressed gases circulate in the housing, and finally escape through the outlet 5. 1

When the device is in operation, the rotation of the fan 55 on the sleeve 33 will cause a circulation within the casing section 2|, of the compressed gases delivered therein from the fluidforcing device or compressor. The compressed gases are thus caused to travel around the oper-' ating parts of the unit exposed above the lubricant reservoir, and will absorb heat therefrom, and will deliver at least a part of the absorbed heat to the casing section 2|, which, being of heat-conducting material, will dissipate the heat readily into the surrounding atmosphere, the remaining heat absorbed by the work material being carried with said material through the outlet H9. The compressed gases themselves are used as a heat-transfer medium for cooling the operating parts. of the unit. It is within the contemplation of the present invention to provide the casing 2| with means, such as .outwardly extending fins, for increasing the heat dissipating capacity of the cover section 2|, however, the provision of such means is not essential to satisfactory operation of the device.

As heretofore mentioned, the device of my present invention is particularly well adapted for use as a compressor in a refrigeration system, and in Figure 1 of the drawings I have shown the outlet I I9 of the unit connected as by means of a pipe or a conduit I43 with a condenser I45 in which the compressed medium delivered from the unit may :be condensed to liquid form by cooling the same. The condenser I45 may be of any suitable or preferred construction, and is preferably cooled by forced-air drafts initiated by a fan I41 powered by an electric motor I49, which is preferably of a character adapted for parallel operation from the source of electrical power used to energize the motor I3 of the unit. The liquefied refrigerating medium delivered from the condenser may be conducted through a conduit I5I, which may include refrigerant drying or dehydrating means, through an expansion valve I53, preferably of the float-controlled type, from which the liquid refrigerant is or may be delivered through a conduit I55 to a refrigerant evaporator or boiler I 51 of any suitable or preferred construction, and in which the liquid refrigerant is evaporated to gaseous form, being absorbed at the boiler during such evaporation. The evaporated refrigerant may be returned from the boiler I55 to the inlet connection I I3 of the sealed motor compressor unit through the conduit II5, thus completing the refrigerating cycle. Such a system is well adapted to refrigerators for domestic service in which the several elements of the system are mounted in a suitable cabinet indicated generally at I59. This cabinet preferably includes a refrigerating compartment I5I, in which the evaporator or boiler I51 is disposed in position to absorb heat from the atmosphere within the refrigerating compartment. The motor compressor unit, the condenser, and its cooling fan, and the expansion valve, may be located in a mechanism chamber I53 formed in the cabinet I59, the compartments IN and I68 being preferably arranged in superposed relationship in the cabinet. Theelementsof the refrigerating system contained inthe compartment I63 may be mounted on a common support element I65 whereby the same may be introduced into and removed from operating position in the compartment I63 as a single ,assembly unit in order thus to facilitate the. manufacture and repair of the refrigerator. With" such an arrangement, the conduits H and I55 may be permanently built into the walls of the cabinet during the course of its construction, while the boiler I51 and the parts carried on the support I65 may be assembled in place and connected with the con- ,fluits H5 and I55 after the cabinet has been fabricated.

As heretofore mentioned, the motors I3 and I49 are arranged for parallel operation from a common electrical power source and, in Figure 2 of the drawings, I have shown an electrical control system for this purpose. Each motor preferably has a plurality of like windings I59 and HI which are connected together at one end to a common conductor I13. The opposite ends of the windings I69 of each motor are connected together to a conductor I15 and the free ends of the windings "I are likewise connected to a conductor I11. The common conductor I13 is connected to a terminal I19 located in a casing I8I, which is or may be located in any convenient position in the cabinet I59, as on the support I65. The terminal I19 is connected by means of a conductor I83 forming a part of a cable I85 extending in the refrigerator cabinet from the casing I8I to a thermostat control casing I81 located adjacent the evaporator I51. The opposite ends of the cable I95 may be provided with detachable connectors I89 and I9I to facilitate connection. The conductor I83, when the parts are assembled and connected for operation, is connected to one side of a switch I93 located in the casing I81, which switch is controlled by thermostat means, manually adjustable as by the control knob I95 which is preferably mounted on the casing I81, the thermostat means including a thermostatic element I91, which extends from the casing I81 into heat-exchange relationship with the atmosphere in the refrigerating compartment in the vicinity of the boiler I51. The thermostatic means is cooperatively associated with the switch I93, so that the same may be opened and closed automatically in response to temperature changes in the refrigerating chamber. The other side of the switch I93 is connected through a manually operable switch I99, preferably mounted in the casing I81, and through a conductor 20I forming a part of the cable I85 to a terminal 203 located in thecasing I8I. The terminal 203 in turn is connected by a conductor 208 forming a part of a cable 205 with means 201 preferably in the form of an electrical plug of ordinary construction, adapted for removable connection in a power outlet socket of the character ordinarily provided in commercial or domestic electric power systems, The cable 205 has another conductor 209 adapted for detachable connection in the power delivery circuit by means of the plug 291, which conductoris connected with a terminal 2" located in the casing I8I. This terminal 2II is electrically connectedwith one end of a A Jsolenoid m, also'locat'edwithin 'the casing I8I,

the other end of which solenoid is connected with a terminal 2I5 mounted in the casing I8I. The

conductor I15, leading from the motor winding I69, is connected with this terminal 2I5; When the plug 201 is connected in an external power circuit, power will be delivered through the cable 205 to the terminals 2 and 203 in order to energize a circuit including in series the conductor ml, the switches I93 and I99, the conductors I83 and I13, the windings I69 of the motors, in parallel, the conductor I15 and the solenoid 2I3. In parallel with the portion of this circuit, which includes the solenoid 2 I3 and the motor windings I69, is an additional circuit including the windings I" of the motors, the conductor I11, and a winding comprising an induction coil 2I1, the opposite ends of which are connected together through a condenser 2I9 and by means of a conductor 22I to one side of the solenoid 2-I3, said induction coil being provided with taps 223 and 225, which are connected to stationary contacts between which is mounted a shiftable blade 221, which moves in response to the current flowing through the solenoid 2 I3 and is adapted to selectively engage one or other of the contacts. The blade 221 is connected to the conductor I11 and consequently controls the character of the power delivered to the circuit both of the parallel circuits including the motor winding are controlled by the switches I93 and I99 so that when the plug 201 is connected in a. power outlet, the motors will remain inactive until both of the switches I93 and I99 are closed. The switch I99, being manually operable, affords manual control for the motors, while the switch I93 provides an automatic control so that the motors will be placed in operation when the temperature in the refrigerating compartment I6I rises above a predetermined value, which may be determined by means of the knob I 95. When the plug 201 is connected to an external power source adapted to deliver single-phase alternating potential between the terminals 203 and 2| I, upon the closure of the switches, alternating current will be delivered through the parallel circuit heretofore mentioned, which includes the windings of the motors. The current delivered to the windings I1I, however, will have a different phase relationship with respect to that delivered to the windings I69 because of the reactive effect imparted by the induction coil 2I1 and the condenser 2 I 9. At the instant of starting, the switch 2I1 will engage one or other of the contacts 223, 225, sov that the proper phase difference for starting the motors will be imparted to the current delivered through the several windings. As the motors reach operating speed, however, the'blade 221 will engage the other of said contacts 223, 225, in order to alter the phase relationship of the current delivered to the windings, it being understood that the phase relationship of current required in the severalwindings for maximum efficiency varies during starting and normal operation of the motors.

The electrical system also includes a circuit 229 including a lamp 23I and a control switch 233, said circuit being connected between the conductor 20I of the cable I85 and another conductor 235 contained in said cable and connected to the terminal 2 so that whenever the'plug 201 is connected to the external power source, the lamp III will be energized providing the switch 233 is closed. The lamp 23! is arranged in any suitable or convenient position within the compartment "I and the switch 233 is arranged to cooperate with the door usually provided in domestic refrigerators for giving access to the compartment I". The switch III cooperates with the door so that it is normally held in open position whenever the door is closed. When the door is open, however, the switch 233 closes'so that the lamp 23l provides illumination for the compartment IBI whenever the door giving access thereto is open.

It is thought that the invention and numerous of its attendant advantages will be understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction, and arrangement of the several parts without departing from the spirit or scope of my invention, or sacrificing any of its attendant advantages; the forms herein described being preferred embodiments for the purpose of illustrating my invention.

Having thus describedmy invention, what I claim as new and desire to secure by Letters Patent is as follows:

1. A machine comprising a base providing an upstanding pedestal having cylindrical side walls, a piston element carried on said pedestal in position extending above the top thereof, a cylinder element enclosing the piston and having portions journalied on the cylindrical side walls of the pedestal, means to admit a fluid work medium to said cylinder, the side walls of said pedestal having a groove forming, with the walls of the cylinder element, an outlet duct for the work medium, said outlet duct communicating with the space within the cylinder at the top of the pedestal and being connected with an opening in the cylinder walls substantially below the top of the pedestal.

2. A machine comprising a base providing a upstanding pedestal having cylindrical side walls,

" a piston element supported by said pedestal in position extending above the upper end thereof, said piston having lesser diameter than the pedestal and having itsside' surface in alignment with the cylindrical wall of the pedestal on one side thereof, a cylinder element enclosing the piston and havingdepending portions embracing and journalledfor rotation on the cylindrical walls of the pedestal whereby to provide a work space between the piston and the cylinder above the pedestal, said work space having crescent-like cross sectional configuration, an inlet duct for a fluid work medium formed in said pedestal and opening into one horn of the crescent-like work space at the top of the pedestal, and an outlet duct connected with the other horn of the work space and comprising a groove formed in a cylindrical side wall of the pedestal on which the dependent portions of the cylinder are journalied.

3. A machine comprising a base providing an upstanding pedestal having cylindrical side walls, a piston element supported by said pedestal in position extending above the upper end thereof, said piston having lesser diameter than the pedestal and having its side surface in alignment with the cylindrical wall of the pedestal on one side thereof, a cylinder element enclosing the piston and having depending portions embracing and journalied for rotation on the cylindrical walls of the pedestal whereby to provide a work space between the piston and the cylinder above the pedestal, said work space having crescent-like cross sectional configuration, means forming an inlet duct for a fluid work medium communicating with one horn of said crescent shaped work space and a groove formed in a side wall of the pedestal and extending from the top of the pedestal opposite the other horn of the work space to a point substantially below the top of the pedestal, said groove forming with the dependent portions of the cylinder an outlet port from the work space.

4. A machine comprising a base providing an upstanding pedestal having cylindrical side walls, a piston element supported by said pedestal in position extending above the upper end thereof, said piston having lesser diameter than the pedestal and having its side surface in alignment with the cylindrical wall of the pedestal on one side thereof, a cylinder element enclosing the piston and having depending portions embracing and journalied for rotation on the cylindrical walls of the pedestal whereby to provide a work space between the piston and the cylinderabove the pedestal, said work space having crescent-like cross sectional configuration, means forming an inlet duct for a fluid work medium communicating with one horn of said crescent shaped work space and a groove formed in a side wall of the pedestal and extending from the top of the pedestal opposite the other horn of the work space to a point substantially below the top of the pedestal, said groove forming with the dependent portions of the cylinder an outlet port from the work space, the dependent portions of the cylinder element having an opening therein substantially below the top of the pedestal in position communicating with said groove and forming, with the walls of said pedestal, a muffler chamber into which the fluid medium may be discharged through the outlet port substantially without noise, and means forming an outlet for the fluid medium from said muffler chamber.

.5. A machine comprising a base providing an upstanding pedestal having cylindrical side walls, a piston element supported by said pedestal in position extending above the upper end thereof, said piston having lesser diameter than the pedestal and having its side surface in alignment with the cylindrical wall of the pedestal on one side thereof, a cylinder element enclosing the piston and having depending portions embracing and journalied for rotation on the cylindrical walls of the pedestal whereby to provide a work space between the piston and the cylinder above the pedestal, said work space having crescent-like cross sectional configuration, means forming an inlet duct for a fluid work medium communicating with one horn of said crescent shaped work space and a groove formed in a side wall of the pedestal and extending from the top of the pedestal opposite the other horn of the work space to a point substantially below the top of the pedestal, said groove forming with the dependent portions of the cylinder an outlet port from the work space, the dependent portions of the cylinder element having an opening therein substantially below the top of the pedestal in position communicating with said groove and forming, with the walls of said pedestal, a muiner chamber into which the fluid medium may be discharged through the outlet port substantially without noise, and a duct formed in the walls of the cylinder element and providing an outlet for the fluid medium from the muffler chamber.

6. A machine comprising a base providing an upstanding pedestal having cylindrical side walls, a piston element carried on said pedestal in position extending above the top thereof, a cylinder element enclosing the piston and having portionsjournalled on the cylindrical side walls of the pedestal, means .to admit a fluid work medium to said cylinder, the side walls of said pedestal forming, with the walls a: the cylinder element, an outlet duct for the work medium. said pedestal comprising an element removable on the base and the means to admit a fluid work medium to the cylinder comprising a longitudinal channel in the pedestal opening at the opposite ends of the pedestal and communicating with a channel formed in the base.

7. A machine comprising a base providing an upstanding pedestal having cylindrical side walls,

a piston element carried on said pedestal in position extending above the top thereof, a cylinder element enclosing the piston and having portions journalled on the cylindrical side walls of the pedestal, means to admit a fluid work medium to said cylinder, the side walls of said pedestal forming, with the walls ofthe cylinder element, an outlet duct for the work medium, said base comprising a casing enclosing the pedestal, cylinder and piston, and into which casing the work medium, discharged through said outlet duct from within the cylinder, enters.

'8. A machine comprising a base providing an upstanding pedestal having cylindrical side walls, a piston element carried on said pedestal in position extending above the top thereof, a cylinder element enclosing the piston and having portions journalled on the cylindrical side walls of the pedestaLmeans to admit a fluid work medium to said cylinder, the side walls of said pedestalforming, with the walls of the cylinder element, an outlet duct for the work medium, said base comprising a cup-shaped element, and said pedestal being mounted on the bottom of the cup-shaped element in position extending within the walls thereof, and a removable cover for the cup-shaped element enclosing the portions of the piston and cylinder elements which extend above the pedestal, said cover forming with the cup-shaped base a sealed housing for the operating parts, and adapted to form a receiver for forming, with the walls of the cylinder element,

an outlet duct for the work medium, said pedestal providing a bearing channel-communicating at the lower end 01' the pedestal with a lubricant source, said piston having a shaft received in said bearing channel and co-operating means on the shaft and pedestal for delivering lubricant through said channel from said source, and delivering the same within the cylinder for the purpose of lubricating the operating parts of the machine.

10. A machine comprising a base providing an upstanding pedestal having'cylindrical side walls, a piston element carried or said pedestal in position extending above the top thereof, a cylinder element enclosing the piston and having portions journalled on the cylindrical side walls of the pedestal, means to admit a fluid work medium to said cylinder, the side walls of said pedestal forming, with the walls of the cylinder element, an outlet duct for the work medium, said base comprising a cup-shaped element and the pedestal being mounted on the bottom of said cup-shaped element in position extending within the walls thereof, an electric motor having an annular stationary portion mounted on said cup-shaped ele ment in position to-encircle the cylinder element, said motor having a rotary portion fixed on said cylinder in position within the annular stationary portion of the motor, and cover means carried by the cup-shaped element in position to enoutlet duct for the work medium. said pedestal being formed with an upwardly facing bearing receiving said piston eiement,,whereby the same is supported at a desired operating elevation on,

the pedestal, the cylinder element enclosing and resting its weight upon the piston element and movable axially with respect to the piston element in order-to provide for unloading the machine when abnormal loading conditions prevail.

12. A'machine comprising a base providing an upstanding pedestal having cylindrical side walls a piston element carried on said pedestal in position extending above the top thereof, a cylinder element'enclosing the piston and having portions journalled on the cylindrical side walls of the MAHIDN W. KENNEY. 

